Excessive sleepiness

Despite the call some time ago for more attention to the clinical importance of sleepiness in children, (37) the topic remains neglected in child psychiatry and paediatrics. Part of the explanation is that sleepiness is not usually viewed as a medical problem by parents, teachers, and children themselves. The symptoms are often misperceived as laziness, disinterest, depression, or even limited intelligence. Another difficulty is that sleepiness manifests itself in different ways according to age. Extreme degrees of sleepiness will cause a reduction of activity at any age, but lesser degrees in children may produce irritability, overactivity, restlessness, poor concentration, impulsiveness, or aggression. Explanations for such behaviours other than sleep loss or disturbance are more likely to be considered.

The high level of daytime alertness in older prepubertal children may be sufficient to offset a tendency to sleep, providing a different clinical picture of sleepiness than that seen at a younger or older age.

Excessive sleepiness may take the form of a prolonged overnight sleep period, or inappropriate periods of sleep during the day.

Because of these problems of recognition, the prevalence of excessive sleepiness in children and adolescence is not known. Clearly, it is not rare in view of the many conditions causing it, many of which are individually quite common.

It is important to establish that the problem really is excessive sleepiness. Tiredness is an ambiguous term: sleepiness needs to be distinguished from fatigue or lethargy for which different explanations are likely including physical illness, such as anaemia, or endocrine disorders, in which other signs are usually present. Occasionally, excessive sleepiness with long periods in bed or at home is simulated in order to escape from a difficult situation. Detection of such cases requires very careful clinical evaluation and assessment and possibly polysomnography.

Excessive sleepiness is mainly a problem in older children and (especially) adolescents. Many teenagers complain of excessive sleepiness but it has been claimed that very many more than those who seek help are likely to be suffering form chronic sleep deprivation or chronic 'sleep debt'. The adverse effects of this are thought to be wide ranging from underperformance at school, college, or work, to road traffic accidents and other mishaps, as well as antisocial behaviour. (12> Sometimes the situation is complicated by the use of stimulants to stay awake, and alcohol or sedative drugs to get to sleep.

The differential diagnosis of excessive sleepiness can be considered in term of three main categories of causes: insufficient sleep, disturbed sleep, and an increased need for sleep (Table.3).

Table 3 Differential diagnosis of excessive sleepiness in older children and adolescents